Mascara products are very popular. Today, the best selling mascara products have department store sales between one and five million dollars per year in the United States alone. Because of this, significant resources are devoted to the development of innovative mascara products. Innovative mascara products are those that introduce new features to the consumer or that improve upon exiting mascaras by making them perform better or by making them less expensive. Innovation in mascara products may occur in the composition or in the applicator used to apply the composition. Being innovative in the field of mascara products can be a challenge because mascara compositions are one of the most difficult cosmetics to formulate, package and apply. In part, this is owing to the physical and rheological nature of the product. Mascara is a heavy, viscous, sticky and often messy product. It does not flow easily in manufacture, filling or application, while drying out quickly at ambient conditions. It may contain volatile components that make safety in manufacture an issue. Mascara is also difficult because of the target area of application. The eyelashes offer a very small application area, while being soft, flexible, delicate and in close proximity to very sensitive eye tissue. Being flexible, the eyelashes yield easily under the pressure of a mascara applicator which makes transfer of the product onto the lashes difficult. The act of transferring a rheologically difficult product to a small, delicate target and in so doing achieve specific visual effects, is the challenging task of mascara application. Furthermore, mascara is unlike most cosmetic products because more than most cosmetics, the success of a mascara product depends on using the product with the right applicator. The overall consumer experience depends on both the product and on the applicator used to apply the it. A well executed mascara formulation may prove to be a failure in the marketplace if not sold with the right applicator to apply and work the mascara on the lashes to achieve the desired effect. Taken the other way, not every mascara composition is right for every kind of mascara applicator. Therefore, a mascara product that is sold with an otherwise commercially popular applicator, may not be well received by the consuming public, if the mascara composition does not complement the applicator function. For this reason, early in development, mascara formulators should and do consider what type of applicator will best complement their composition. However, to date, applicants are unaware of any disclosure concerning which rheological type of mascara compositions will work better with which types of applicator. By “work better” it is meant that one or more art-recognized properties of mascara application is improved by choosing a particular kind of mascara for use with a particular kind of applicator compared to the same mascara with some other applicator or a rheologically different mascara with the same applicator. “Rheological type” and “rheologically different” mean thixotropic verses anti-thixotropic.
The most common mascara applicator is the mascara brush. A typical mascara brush comprises a core, bristles, a stem and a handle. The core is typically a pair of parallel wire segments formed from a single metallic wire that has been folded into a u-shape. Bristles, usually comprised of strands of nylon, are disposed between a portion of a length of the wire segments. The wire segments, with the bristles disposed therebetween, are twisted or rotated about each other to form a semi-rigid helical core, also known as a twisted wire core. The twisted core holds the bristles substantially at their midpoints so as to firmly clamp them. In this state, the bristles, which are secured in the twisted wire core, extend radially from the core in a helical or spiral manner. Collectively, the radially extending bristles form a bristle portion or bristle head. The imaginary surface of the bristle head, comprising all of the bristle tips, is known as the bristle envelope. Many variations of this brush are known in the art. Although the results of mascara application and customer satisfaction depend on the combination of product and brush, it is useful to separately discuss the performance of each.
Mascara Brushes Characteristics and Performance
An ideal mascara brush may be thought of as one that performs certain functions. These include taking up, in one step, enough product from the mascara reservoir to coat all the lashes of one eye, without having to re-insert the brush into the reservoir. The act of repeatedly reinserting the brush into the reservoir has the effect of incorporating air into the mascara in the reservoir, which causes the mascara to dry out and become unusable faster than it otherwise would. Further, the ideal brush must transfer to the lash enough product to coat the entire lash. That is, having withdrawn from the reservoir an optimal amount of product, the ideal brush must now be able to transfer that product to the lashes. To some degree, the ability of the applicator to take up product from the reservoir and the ability to give off that product to the eyelashes work against each other. In the first instance it is desirable for mascara to stick to the brush so that it can be removed from the reservoir. In the second instance it is desirable for the mascara to unstick from the brush so that it may cling to the lashes. Having deposited the product on the lash, the ideal brush evenly distributes the product over all the lashes. Further, the ideal brush smoothes out any clumps of product which may have been drawn from the reservoir and placed on the lashes. The ideal brush is able to separate and comb out the lashes to give the lashes a clean, well groomed, finished appearance. The ideal brush can be used effectively to touch up or doctor the lashes as needed. Also, a brush that evacuates substantially all of the mascara product from the reservoir is ideal. To date, a single brush that performs all of these functions optimally is believed not to exist. This is because different bristle types and configurations are better or worse at one or more functions. Therefore, a typical mascara brush represents a trade-off between maximizing some brush functions at the expense of others. The finally selected brush depends on the nature of the mascara product with which it is to be used. For example, a mascara formulated to give volume to the lashes should ideally be sold with a brush suitable for that purpose.
The current state of mascara brush art is such that some parameters known to affect various brush functions have been identified. Generally, the values of these parameters cannot be adjusted to produce an ideal brush, that is, a brush that performs all the desired functions satisfactorily. Because of this trade-off situation, there exist a great number of variations of the typical mascara brush. Some brushes seek to maximize some functions at the expense of others, while other brushes attempt to split the difference, so to speak, by performing many functions somewhat satisfactorily. Arriving at these variations is frequently no more than selecting appropriate values for the various known parameters. A review of those parameters that are recognized by a person of ordinary skill in the art to be results-effective is in order.
The shape of the wire core. While a straight core is still the most common in the cosmetics marketplace, bent wire cores are also known. For example, a core in the shape of an arc that attempts to match the shape of the eyelid are known (U.S. Pat. No. 5,137,038, U.S. Pat. No. 5,860,432 and U.S. Pat. No. 6,237,609). This shape, it is supposed, may be more efficient at coating the lashes. In U.S. Pat. No. 5,761,760 the wire core is bent to form a closed loop. The purpose of the loop is to provide a reservoir for retaining and transferring mascara or other pasty product from the mascara container to the eyelashes. Because this brush applies a relatively large dose of mascara, it is suitable for increasing length and volume of the lashes. It may be less suitable for combing, declumping and separating the lashes.
Stiff verses flexible bristles. It is generally recognized in the art that stiffer bristles are better than more flexible bristles when it comes to loading the brush with mascara from the reservoir. Stiffer bristles are thought to retrieve more product from the reservoir than do more flexible bristles. As the brush is withdrawn from the reservoir it passes through a wiper one function of which is to spread the product as evenly as possible over the surfaces of the bristles to provide a neater brush. In this way, portions of the brush with relatively high concentrations of product may be thinned out and some portions with relatively little product may be loaded. Generally, bristles that are too flexible will become matted down upon passing through the wiper and thereafter may remain stuck together because mascara is typically quite tacky. Having been removed from the reservoir, the loaded brush is made to contact the eyelashes. At this point, it is generally understood that a brush with softer, more flexible bristles in a dense array is better for transferring the mascara to the eyelashes by affecting as much transfer as possible. Once the eyelashes are loaded, however, it is generally understood that an applicator brush having stiffer bristles and a relatively open bristle envelope or sparse array (so as to be more comb-like) is needed to declump the product and separate the lashes. Given this situation, various attempts have been made to provide a mascara brush that combines the benefits of both stiff and flexible bristles. For example, a brush that is said to provide good application and combing characteristics is shown in U.S. Pat. No. 4,861,179. Disclosed is a brush having a combination of conventional soft bristles and conventional stiff bristles. Another example of a brush said to provide good application and combing characteristics is shown in U.S. Pat. No. 5,238,011 which discloses bristles made of a soft material having a shore hardness of 20 A to 40 D (a conventional bristle typically has a durometer of over 85 D), and a large diameter in a range of 3.9 to 13.8 mil (10 to 35 hundredths of a millimeter), which is at least 1.5 mil (˜4 hundredths of a millimeter) wider than a typical soft polyamide bristle. In this patent, the diameter is said to be sufficiently large to prevent too high a degree of suppleness. The resulting brush is said to have the same degree of suppleness or softness as a conventionally softer brush. Accordingly, the bristles are equivalent in stiffness to conventional bristles.
While these references may disclose brushes suitable for the application and combing of conventional mascara, currently preferred mascaras have significantly higher resting viscosity (two million CPS and above). These higher viscosity mascaras tend to collapse bristles of conventional stiffness, thus rendering a brush having bristles of conventional stiffness ineffective for purposes of application or combing. Accordingly, some of the forgoing brushes would not be suitable for use with such higher viscosity mascaras. Furthermore, these brushes do not offer the user the opportunity to compensate, at will, for one or the other shortcoming (i.e. bristles too soft or too stiff). Once these brushes leave the factory, they are what they are and cannot be altered by the user.
Bristle length and density. As a general rule, longer and more densely spaced bristles retrieve more product from the reservoir and deposit a thicker coating of mascara on the lashes than shorter, less densely spaced bristles. This is simply because in the former case there is more surface area on which to accumulate mascara. However, one problem with densely spaced bristles that carry a large quantity of mascara is that the lashes may not be able to penetrate the space between the bristles. This is simply because the lashes are so flexible. Also, because densely spaced bristles carry a lot of product from the reservoir while tending not to separate the lashes, there is a tendency for the lashes to clump together during application. With such a brush, it is not easy to obtain an even coat on the lashes. A lot of brushing, effort, skill and patience on the part of the user is required. In contrast, a brush with less densely spaced bristles may penetrate the lashes easily, but delivers less product, perhaps an insufficient coating to the lashes. To overcome this, the procedure must be repeated multiple times for each lash. It is generally understood in the art, that the more times the making up procedure is repeated, the more chance there is to mess up the entire application of mascara. The longer it takes to perform the application, the more complicated it becomes. If the product already applied to the lashes is setting up and drying out while new mascara is still being applied over it, an even, clean appearance may be very difficult to achieve. It may become necessary to clean the eyelashes and start again. Mascara application is known to be a bit of a skill and a bit of an art, wherein less is sometimes more.
U.S. Pat. No. 4,887,622 discloses a low density mascara brush, the bristles of which are spaced from 10 to 40 bristles per turn of the twisted wire core. As discussed in the '622 patent, then-conventional brushes had about 50 to 60 bristles per turn with the per-turn pitch being about 2 mm and the bristle diameter being about 0.08 mm maximum. It is alleged that 50-60 bristles per turn is sufficient to take up enough mascara to coat the lashes, but that brushes of this bristle density do not distribute the product very well, resulting in blobs of product and wasted time. The alleged improvement consists of reducing the bristles per turn to 10-40 while using bristles of a larger diameter (0.10 to 0.25 mm). Though there are fewer bristles to carry product, more product may carried by each bristle. The lower density permits the bristles to penetrate the lashes and provide an even coat of product.
Mixing bristle types. U.S. Pat. No. 4,586,520 disclose a mascara applicator whose brush contains alternating rows of long and short bristles. It is alleged that this arrangement of alternating rows of long and short bristles allows for easier application of mascara while simultaneously combing and separating the eyelashes. U.S. Pat. No. 5,345,644 discloses a mascara brush having two different types of bristles intermingled along the axis of the brush. One type is a smaller diameter (0.06-0.13 mm), higher melting point thermoplastic bristle, the other is a larger diameter (0.13-0.30 mm), lower melting point thermoplastic bristle. It is alleged that strong, distinct make-up effects are achieved with this type of brush.
Sectioning bristle types. U.S. Pat. No. 5,357,987 and EP 0511842 disclose mascara brushes having a bristle array with a discontinuous profile. There is a tip portion having one overall size and shape and a proximal portion having a second size and shape. The main reason for this is to provide a single brush in sections, each section of which is better than the other section at performing some application tasks.
U.S. Pat. No. 5,482,059 combines sectioning and mixed bristle types within one section. This patent discloses a mascara brush having three sections and three types of bristles. The brush portion has a larger diameter middle section comprised of a combination of soft and stiff bristles in random configuration, and two end sections comprised of hollow filaments which preferably become progressively shorter towards the ends of the brush portion. The end sections exhibit less bristle density than the middle section. This improved brush configuration allows for optimal one-stroke mascara application.
Shape of the envelope. The most conventional envelope shape is the tapered spiral or helical array of bristles. One variation on this theme is U.S. Pat. No. 5,595,198 in which a helical groove is present along the length of the bristle array due to the use of specifically positioned, shorter bristles. The groove is for carrying larger quantities of product than would otherwise be possible. A great many envelopes shapes have been introduced into the art, each purporting to be an improvement on one or more aspects of mascara application.
Bristle shape. U.S. Pat. No. 4,993,440 discloses the use of bristles having capillary channels along their length. U.S. Pat. No. 5,567,072 discloses bristles with a slotted cross sectional configuration. U.S. Pat. No. 5,595,198 discloses bristles with an L-shaped cross section. Tubular bristles are disclosed in U.S. Pat. No. 4,733,425.
Other applicator features. Mascara applicators that are said to have performance enhancing features apart from the applicator head, are known. Ergonomic handles and comfort grips are known. US patent publication 2002-0168214 discloses a mascara handle grip made from one or more deformable elastomers and having a dual-tapered portion such that two tapered sections meet at a narrowest point along the dual-tapered portion, and wherein the cross section of one or both tapered sections is elliptical. The use of this or any other deformable grip on a vibrating mascara applicator system is unknown to the applicant.
Non conventional mascara applicators. In the quest for the ideal mascara applicator some have avoided the issue of stiff verses flexible bristles by not using bristles. U.S. Pat. No. 3,892,997 describes an applicator comprising a central shaft (or core) along the length of which rigid triangular plates outwardly project, many such plates being parallel to each other. The regularly spaced plates are reportedly suitable for loading, transferring, coating and separating. U.S. Pat. No. 4,545,393 described a bellows capable of being lengthened or shortened by the user as required. The stacked “teeth” of the bellows provide surfaces for holding mascara and the spacing between the teeth allows the eyelashes to be coated and separated. U.S. Pat. No. 5,094,254 describes a central core with a ribbed profile. The individual ribs provide surfaces for holding mascara and the spacing between the ribs allows the eyelashes to be coated and separated. U.S. Pat. No. 5,816,728 describes a beaded mascara applicator, that is a mascara applicator having one or more beads disposed on a central axle extending longitudinally from an elongated rod and handle. A first preferred embodiment comprises a single cylindrical bead molded from plastic and having a series of longitudinally spaced grooves along the length of the bead. A second preferred embodiment comprises a plurality of about 5 to 7 beads disposed on a metal axle and retained by means of a flat-headed pin. The beads are capable of individually or collectively rotating about the axle to create optimal mascara application and lash separation. U.S. Pat. No. 6,345,626 and U.S. Pat. No. 6,691,716 disclose a mascara applicator having an array of independent discs which compress during withdrawal from a container so that excess product can be removed from the applicator by a wiper. After passage through the wiper, the discs return to their expanded position by the action of a spring. The compressing of the discs during withdrawal allows a controlled amount of product to remain on the applicator for application by the consumer, and the returning of the discs to their expanded position by the spring causes the discs to assume a configuration which allows the applicator to effectively comb and separate the eyelashes.
As can be seen from the foregoing brief survey of the mascara applicator field, many innovations and proposals have been put forward. None of these proposals deal with substantially, measurably altering the flow characteristics of a mascara product at the time of application. Nothing in the prior art anticipates or suggests a vibrating mascara applicator capable of altering the viscosity of a mascara in a controlled fashion, nor the benefits of such. To the best of the applicant's knowledge, a brush that offers to the user the opportunity to alter the performance of both the applicator and mascara at the time of application, is unknown in the art. Simultaneously, it will be appreciated from the discussion to follow, that any of the mascara applicators heretofore described, indeed virtually any mascara applicator, would assume additional performance advantages if the such were made to vibrate in the manner herein described.
Rotating Mascara Brushes. Mascara brushes that rotate during application are known. Rotation occurs around the long axis of the applicator rod, a motion that is unlike the vibrating applicator of the present invention. U.S. Pat. No. 4,056,111 describes a motor-driven, rotatable mascara brush. The motor may comprise a rewindable spiral spring (i.e. a clock-work motor) or a battery powered motor may be used. U.S. Pat. No. 6,565,276 discloses a battery powered motor, rotating mascara brush head. In either case, the brush can be made to rotate in either direction to accommodate left and right handed operation for either eye. The stated advantage is convenience and less movement required by the user. U.S. Pat. No. 4,397,326 describes a non-motorized mascara brush, the head of which is free to rotate and does so when the brush head contacts the eyelashes during application. It is the act of brushing that causes the rotation. It is claimed that the rotation of the brush head allows more mascara to be deposited on the lashes in a single application than other wise would be possible. U.S. Pat. No. 4,632,136 describes a rotating brush applicator for mascaras having a viscosity range from 1,500 to 25,000 poise at ambient temperatures. The brush has 75-150 bristles per quarter inch and a motor housed in the handle of the applicator turns the brush. These parameters were chosen to allow the bristles of a rotating brush loaded with mascara to penetrate and move though the lashes. The author noted that rotating brushes cannot not penetrate the eyelashes when used with formulae more viscous than 25,000 poise and/or bristle arrangements more dense than 150 bristles per quarter inch. In that case, the rotating brush only bends the lashes back as it presses against them. Also, it is explicitly disclosed that the brush is not made to rotate until after the brush is removed from the reservoir. No shearing of the product takes place in the reservoir because the purpose of the rotating brush is not to shear the product, it is to separate and comb the lashes. Because of this, the invention was limited to a range of mascara viscosity and less dense bristle arrangement. Also, no motor or drive mechanism are disclosed for affecting the brush rotation and no frequency is disclosed. JP 2005-095531 discloses an electric motor that operates a gear that rotates a brush head at fixed speed. The rotation occurs around the long axis of the applicator rod. At the time of filing this application, only an abstract of JP 2005-095531 is available to the applicant. No further details or alleged benefits are known at this time.
These are unlike the present invention where the brush does not rotate about the axis of the brush, rather it oscillates laterally at relatively high speed, in the reservoir and out of the reservoir to shear the product and substantially alter the product's viscosity. None of these references disclose a mascara brush that vibrates or oscillates in a direction perpendicular to the long axis of the rod. None of these references disclose the mascara applicator with a brush head that vibrates while in the reservoir, as well as during application to the lashes. If further seems questionable whether the clock-work motor (wind-up motor) of U.S. Pat. No. 4,056,111 and the “low speed” motor preferred in U.S. Pat. No. 6,565,276 would be able to rotate when the brush head is immersed in the viscous mascara product in the reservoir and therefore, whether they could shear the product in the reservoir to substantially alter its viscosity. Obviously, the non-motorized brush of the '326 patent cannot rotate when immersed in mascara, and therefore is unable to shear the product. In contrast, the oscillating or vibratory motion of the present invention is capable of substantially shearing a viscous mascara. The '111 and '276 brushes also require added complexity to effect the reversible motor feature, gears and pinions and such. The device of the JP '531 publication also has gears. In contrast, the motor of the present invention does not have gears nor need to be reversible in order for the motion of the brush head to be effective. The motor used in the present invention is, therefore, simpler. Furthermore, the present invention may be used over the whole range of mascara viscosities, not being limited as is the '136 brush. The lateral motion of a brush according to the present invention is thought to be superior to the '136 applicator regarding separating the lashes and preventing clumping. For example, the vibrating movement of the brush head naturally carries and pushes the mascara toward the baseline of the eyelash, where some users may be too squeamish to go. A brush rotating about the long axis of the rod does not provide this advantage.
Other electric brush devices. Electric toothbrushes are known. Despite their superficial similarity to motorized mascara brushes, the typical electric toothbrush also has a number of significant differences with them. These differences make a toothbrush ineffective for performing many of the functions of a mascara brush, as discussed above. Generally, toothbrush bristles have different stiffness requirements than those of a mascara brush, owing to their different purposes and areas of use. Also, toothbrush bristles are generally longer, as much as two to five times longer than mascara brush bristles. The toothbrush bristles are located only on one side of the head as opposed to generally surrounding the head. A toothbrush does not have a working tip at the distal end of the head as do most mascara brushes. The envelope of the toothbrush is a two dimensional plane rather than a three dimensional surface. Toothbrush bristles are generally more densely packed than those of a mascara brush and they are usually all the same length, unlike most mascara brushes which have varied length bristles. Toothbrush bristles are generally supported by a relatively large, flat base that is located at the exterior of the bristle array as opposed to the center of the bristle array. Such a base cannot fit into a common mascara tube and if it could it would become covered with mascara making a mess and wasting a lot of mascara. Owing to their many differences, mascara brushes and toothbrushes are generally patentably distinct.
Vibrating razors and dental flossers are also known. Generally, these may include a handle in which is located an electric motor, the operation of which produces a vibration. The similarities between these devices and that of the present invention end there. For obvious reasons a shaving razor and a dental flosser are wholly unsuitable for mascara application. U.S. Pat. No. 5,299,354 discloses a vibrating wet shave razor. The be effective for shaving, the frequency of the electric motor is disclosed as being 5000 to 6500 revolutions per minute. The amplitude of the vibrating blade that is effective for shaving is disclosed as 0.002 to 0.007 inches.
Application Habits. While there are many variations in the way mascara users apply the product, there is some consensus on the best methods for so doing. In “The Beauty Bible,” (by Paula Begoun, 2nd ed., June 2002, Beginning Press, ISBN 1-877988-29-4), herein incorporated by reference in its entirety, the author recommends the following. “The traditional upper-lash application of rotating the mascara wand by round-brushing from the base of the lashes up to cover all the lashes around the entire eye is the most efficient, expedient method.” The author further notes, “Apply mascara to the lower lashes by holding the wand perpendicular to the eye and parallel to the lashes (using the tip of the wand). This prevents you from getting mascara on the cheek. It also makes it easier to reach the lashes at both ends of the eye.” Also, after applying the mascara in whatever manner, some women brush out the lashes with a separate brush or comb.
Mascara Compositions Characteristics and Performance
Turning now, to mascara compositions, there is an established vocabulary for discussing their performance characteristics. Each of these characteristics can be evaluated and assigned a number on a random scale, from 0 to 10, say, for purposes of comparison during formulation. “Clumping”, as a result of mascara application, is the aggregation of several lashes into a thick, rough-edged shaft. Clumping reduces individual lash definition and is generally not desirable. “Curl” is the degree to which a mascara causes upward arching of the lashes relative to the untreated lashes. Curl is often desirable. “Flaking” refers to pieces of mascara coming off the lashes after defined hours of wear. The better quality mascaras do not flake. “Fullness” depends on the volume of the lashes and the space the between them, where “sparse” (or less full) means there are relatively fewer lashes and relatively larger separation between the lashes and “dense” (or more full) means the lashes are tightly packed with little measurable space between adjacent lashes. “Length” is the dimension of the lash from the free tip to its point of insertion in the skin. Increasing length is frequently a goal of mascara application. “Separation” is the non-aggregation of lashes so that each individual lash is well defined. Good separation is one of the desired effects of mascara application. “Smudging” is the propensity for mascara to smear after defined hours of wear, when contacting the skin or other surface. Smearing is facilitated by the mascara mixing with moisture and/or oil from the skin or environment. “Spiking” is the tendency for the tips of individual lashes to fuse, creating a triangular shaped cluster, usually undesirable. “Thickness” is the diameter of an individual lash, which may be altered in appearance by the application of mascara. Increasing thickness is usually a goal of mascara application. “Wear” is the visual impact of a mascara on the lashes after defined hours as compared to immediately after application. “Overall look” is one overall score that factors in all the above definitions. It is a subjective judgment comparing treated and untreated lashes or comparing the aesthetic appeal of one mascara to another. The ideal mascara will possess all of the desirable properties while avoiding the undesirable.
Often, the formulator is interested in achieving thicker, fuller, well separated lashes. Characteristics like clumping and spiking tend to work against this, and a developer can improve one or more characteristics only at the expense of others. For example, to increase the fullness of a particular mascara, conventional wisdom suggests adding more solids (wax) to the composition. However, a disadvantage of doing this is that it tends to increase clumping of the composition and decrease the user's ability to separate the lashes. A high level of solids can also create a negative sensorial effect because the high concentration of solids makes the mascara difficult to spread over the lashes. The result can be tugging on the lashes, discomfort associated therewith and a poor application. The art of conventional mascara formulation is a balancing act between separation and volumizing, between too much of one and not enough of the other. One of the advantages of the present invention is that the definitions of “too much” and “not enough” are expanded beyond what has been achievable up to now. This increased formulation flexibility has advantages for the formulator, the manufacturer and the consumer.
Conventional mascara formulations include oil-in-water emulsion mascaras which may typically have an oil phase to water ratio of 1:7 to 1:3. These mascaras offer the benefits of good stability, wet application and easy removal with water, they are relatively inexpensive to make, a wide array of polymers may be used in them and they are compatible with most plastic packaging. On the down side, oil-in-water mascaras do not stand up well to exposure of water and humidity. Oil-in-water mascaras are typically comprised of emulsifiers, polymers, waxes, fillers, pigments and preservatives. Polymers behave as film formers and improve the wear of the mascara. Polymers affect the dry-time, rheology (i.e. viscosity), flexibility, flake-resistance and water-proofness of the mascara. Waxes also have a dramatic impact on the rheological properties of the mascara and will generally be chosen for their melt point characteristics and their viscosity. Inert fillers are sometimes used to control the viscosity of the formula and the volume and length of the lashes that may be achieved. Amongst pigments, black iron oxide is foremost in mascara formulation, while non-iron oxide pigments for achieving vibrant colors has also become important recently. Preservatives are virtually always required in saleable mascara products.
There are also water-in-oil mascaras whose principle benefit is water resistance and long wearability. These mascaras may typically have an oil phase to water ratio of 1:2 to 9:1. Various draw-backs of water-in-oil mascaras may include: difficulty in removing the product from the lashes, a long dry-time, a high degree of weight loss from the product reservoir, generally less compatibility with packaging materials than oil-in-water mascaras and a relatively low flash point. Water-in-oil mascaras are typically comprised of emulsifiers, solvents, polymers and pigments. Volatile solvents facilitate drying of the mascara. Polymers play a similar role in water-in-oil mascaras as in oil-in-water discussed above, although in the former, an oil miscible film forming polymer is recommended. The same classes of pigments may be used in water-in-oil mascaras, as in oil-in-water. Here though, a hydrophobically treated pigment may provide improved stability and compatibility.
Dry-out of mascara in the reservoir is a common problem. One way to limit dry-out is to provide mascara in cylindrical tubes or bottles that have a small cross sectional area, so that very little mascara contacts the ambient air. Nevertheless, often, some portion of the mascara in the reservoir becomes unusable because of dry-out. Dry-out may occur if too much water evaporates from the reservoir. The amount of evaporative water depends on the length of time the reservoir is exposed to the ambient air. Also, the act of repeatedly immersing the brush into the reservoir may incorporate air into the product, thus accelerating the rate of dry-out. Because of this, it is better to immerse the brush into the reservoir as few times as possible and the act of “pumping” the applicator to load product onto it should be avoided. In solvent-containing systems, dry-out occurs if too much solvent is allowed to volatize from the product. Ideally, the solvent would remain in the product until it is applied to the lashes and only then would the volatile component dissipate to create the drying effect. However, as typically happens, some solvent is lost from the product in the reservoir each time the product is exposed to the air. Therefore, normal use of the product causes the product to deteriorate. Frequently, what remains in the reservoir goes to waste, having dried out too much to be used.
Applicators for Altering the Viscosity at Time of Use
For the vast majority of mascara products on the market, no mechanism is provided to alter the rheological and application properties of the mascara at the time of application. In the literature, U.S. Pat. No. 5,180,241 describes a mascara container and conventional mascara brush wherein the container includes a helical spring on the inside of the container, through which the brush must pass on its way out of the container. The product on the brush is said to have its thixotropy broken by the action of the loaded bristles flexing and straightening as they squeeze through the turns of the spring. The reference does not quantify in any way to what degree the viscosity is affected nor how long the effect lasts. Disadvantages of this system include the fact that the mascara is only sheared for a moment while the brush is passing through the spring. There is no mechanism for longer, continuous shearing for an extended period of time, several seconds or minutes. There is no shearing after the brush is removed from the container, for example, while the mascara is being applied to the lashes. During this time, the viscosity, to the extent that it may have been reduced, is building back to its original value, so that the full, if any, advantage is not even realized. If a user attempts to increase the amount of shearing by repeatedly pumping the applicator through the spring, this will have the detrimental effect of incorporating air into the product and drying it out, as discussed above. This would actually produce a result opposite to that intended, causing the product to thicken ad flow less well. Also, in this reference there is no mention of mascaras that are capable of anti-thixotropic behavior (or thickening when sheared) and no suggestion of how this system may affect future mascara formulations. This is unlike the present invention wherein the viscosity is substantially, measurably altered by shearing, the duration of which is controllable by the user and which duration may be several seconds or minutes. Pumping the applicator is not necessary to cause shearing and anti-thixotropic mascaras can benefit from the present invention as well as thixotropic. Also, the present invention opens the way for changes in the way mascaras are conventionally formulated.
In U.S. Pat. No. 5,775,344, the mascara product is heated just prior to and/or during application. Generally, heat is supplied by a heating element powered by a battery. The heating element may be in the container that holds the mascara or in the brush that is dipped into the mascara. The '344 patent discloses cosmetic product devices that heat the entire contents of a reservoir prior to an application, each time this device is used. But it should be appreciated that not all mascaras can be temperature cycled without damaging the product. For mascaras that will be changed structurally or chemically by the application of too much heat or from being too often heated, these devices are wholly unsuitable. This is unlike the present invention, wherein the product remaining in the reservoir is not heated and remains in good condition for future use. Another disadvantage of these devices is the need for thermal insulation to keep the heat inside the reservoir. The insulation makes these devices more complex and costly than the present invention, wherein the reservoir is neither heated nor insulated.
Virtually all mascaras can, if shearing means are provided, exhibit some degree of thinning or thickening behavior. With a non-vibrating brush, a user cannot significantly shear a mascara to cause it to exhibit its thinning or thickening behavior. Even if some alteration of the product's viscosity did occur as a result of a conventional applicator shearing the product in the container, the amount would be insignificant as compared to the present invention and no significant advantage would accrue to the user. To the best of the applicant's knowledge, the fact that a mascara is capable of exhibiting thinning or thickening behavior has never been exploited to any significant degree in the application process. More specifically, the existence and use of a vibrating mascara brush to alter the viscosity of a mascara at the time of application are hitherto, unknown.